One of the most popular boys at Seika High, Usui appears to take little interest in anything and prefers to observe things as they unfold, though proves to be extraordinarily talented in numerous areas. He develops an interest in Misaki and is the first to learn she is working at a maid café, but chooses to keep her secret and soon falls in love with her. While she dismisses his behavior simply as harassment and teasing (but claims he just wanted to see her "interesting expressions"), he continues to watch over and protect her no matter what it takes like injuring himself in the process, as well as offering insightful advice on how to deal with the boys at Seika effectively and fairly. He appears to be the only male student at school that Misaki is willing to speak to as an equal. Little is known about Usui's background and he is reluctant to speak about it, though he reveals a willingness to tell Misaki. He has an older brother and lives alone in an apartment.

At one point in the anime, he asked her to be his maid for one day because he wants her to be his maid and his only; however, she denied it. He even confessed his feelings to Misaki numerous of times, but that only caused more confusion for her. He also wanted to know want she thought of him, but according to Usui, Misaki wasn't being honest to herself, as a result she didn't know what to think of him.

In Kaichou wa Maid-sama!: Omake dayo!, a special, Misaki asked Usui about his kitten that he found in the streets and brought it home as his pet, Hinata then asked what he named it, he replied that it doesn't have a name. Suzuna wanted everyone to come up with a good name for the kitten. Finally, Usui asked Misaki to name it, she came up with Licht that she saw on a can, thinking it was a good name. He then agreed on the name. Licht means light in German. Even though Licht scratches and hisses at him, he continues to be kind to it, and in the end, Licht shows some warm affection towards him.

As revealed in Chapter 52, his real name is "Takumi Walker," taking on his mother's name. His father Yuu Hirose was revealed in chapter 74 and seen in chapter 75. Usui later transfers to Miyabigaoka High School due to the request from his family. In the manga, he travels to England to confront his family issues.

In the manga, Usui and Misaki start dating. In the last chapter he becomes a doctor and marries Misaki.